| The excess sludge produced by the municipal wastewater treatment plant has the characteristics of high yield,high moisture content,difficult in dehydration and long organic stable time,which makes the disposal and disposal of sludge become a key point for the operation and management of the sewage treatment plant.In order to reduce the difficulty of treatment and disposal of sludge,the ultrasonic,Fenton and ultrasonic coupling Fenton pretreatment methods were used to study the effect of cracking sludge,following by using the supernatant of Fenton oxidation sludge as carbon source for MFC,then study the degradation of anode substrates and the performance of electricity generation under different cathode conditions.Finally,metagenomic sequencing technology was used to study the microbial community and abundance of inoculated sludge and anode carbon felt.Main conclusions are as follows:?1?The results of ultrasonic disintegrate sludge show that ultrasonic can significantly change the physicochemical properties of sludge.With the increase of ultrasonic density and the prolongation of reaction time,the concentration of SCOD,proteins,polysaccharides,NH4+-N,TN and TP in the supernatant increased significantly and the sludge particle size decreased significantly.After reaction for 30 minutes at ultrasonic density of 0.8 W/mL,the concentration of SCOD,NH4+-N,TN,TP,protein,and polysaccharide increased by 20.3times,5.9 times,11.0 times,0.9 times 9.4 times and 12.0 times than the sludge before reaction,respectively.Moreover,the average particle size of sludge decreased by 86.1%compared with untreated sludge.Under experimental ultrasonic density,the SCOD value increases linearly with the reaction time,which means that cracking sludge gain a faster rate under higher ultrasonic density.Meanwhile,ultrasonic energy also shows a significant effect on the performance of sludge dewatering,with the increase of ultrasonic energy,the dewatering performance first appeared a transient improvement and then deterioration,the SRF showed a slight decrease and then a substantial increase.By fitting the specific surface area of sludge particles to sludge SRF and the concentration of EPS to sludge SRF,it can be seen that there is a significant linear relationship between the specific surface area of the particles,the EPS concentration and the sludge SRF.?2?The results of Fenton oxidation sludge show that when at 40°C,the initial pH value is 3,the dosage of H2O2 is 9.99g/L,the dosage of Fe2+is 0.75g/L,and the reaction time is 120mimutes,the concentration of SCOD,protein,polysaccharide,NH4+-N and TN increased by 15.8 times,13.4 times,11.3 times,6.6 times and 13.1 times compared with the raw sludge,respectively,the sludge SRF and average particle size decreased by 77.3%and53.9%compared with the raw sludge,respectively.The results of ultrasonic coupling Fenton oxidation indicate that coupling technology can improve the effect of cracking sludge.However,when coupled with 0.4 W/mL ultrasonic density reacts for 120 minutes,the concentration of SCOD was ultrasonic>coupling>Fenton under three methods.Meanwhile,with the increase of ultrasonic density and reaction time,the sludge SRF gradually increases.?3?The results of using Fenton oxidation sludge supernatant as the MFC anode substrate show that under the cathode of 50 mmol/L potassium ferricyanide,aeration and200 mg/L potassium permanganate.Through a period of stable operation,the degradation efficiency of SCOD were 70.66%,67.67%and 74.66%,the coulomb efficiency were13.69%,9.59%,and 5.61%,the maximum power densities were 8.15W/m3,1.63W/m3 and1.98W/m3,the internal resistance were 36.73?,230.8?,and 339.8?,respectively,which show a better performance of electricity production compared with the raw sludge supernatant as anode substrate.By the metagenome sequencing technique to test the microbial community of inoculation sludge and anodic carbon felt.The results indicated that at the phyla level,the absolutely dominant species were Proteobacteria,Chloroflexi and Bacteroidetes of the two samples.At the genus level,it suggested that the inoculation sludge mainly dominated by Unclassified,while the bacteria distribution on the carbon felt was mainly based on the genus of the Petrimonas,Comamonas and Bellilinea. |
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